U.S. patent application number 11/569717 was filed with the patent office on 2008-03-06 for fluid permeable composite material and process for same.
Invention is credited to John Arthur Cummins.
Application Number | 20080058461 11/569717 |
Document ID | / |
Family ID | 35450861 |
Filed Date | 2008-03-06 |
United States Patent
Application |
20080058461 |
Kind Code |
A1 |
Cummins; John Arthur |
March 6, 2008 |
Fluid Permeable Composite Material and Process for Same
Abstract
A fluid permeable material is disclosed. The fluid permeable
material is suitable for use as a paver, brick, tile, stormwater
entry grate and the like, without being limited thereto. The fluid
permeable material described in this invention is light weight and
has a hight characteristic breaking strength, and flexural
strength. The fluid permeable material described allows fluid to
flow freely through the structure without impacting on the
structural integrity of the composite material, and filters
particulate contaminants from the fluid as it passes through the
structure.
Inventors: |
Cummins; John Arthur;
(Queensland, AU) |
Correspondence
Address: |
RENNER OTTO BOISSELLE & SKLAR, LLP
1621 EUCLID AVENUE
NINETEENTH FLOOR
CLEVELAND
OH
44115
US
|
Family ID: |
35450861 |
Appl. No.: |
11/569717 |
Filed: |
May 30, 2005 |
PCT Filed: |
May 30, 2005 |
PCT NO: |
PCT/AU05/00751 |
371 Date: |
November 28, 2006 |
Current U.S.
Class: |
524/494 ;
524/556 |
Current CPC
Class: |
Y02A 30/32 20180101;
E01C 11/225 20130101; E01C 11/226 20130101; E03F 5/0404 20130101;
E01C 11/165 20130101; E01C 7/30 20130101; C08L 33/066 20130101;
E01C 5/20 20130101; Y02A 30/30 20180101; E03F 1/00 20130101; C08L
33/066 20130101; C08L 2666/20 20130101 |
Class at
Publication: |
524/494 ;
524/556 |
International
Class: |
C08K 3/40 20060101
C08K003/40; C08L 31/00 20060101 C08L031/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 28, 2004 |
AU |
2004902827 |
Claims
1. A curable composition for producing a fluid permeable composite
material comprising: a particulate material; and a binding agent
including: a binder; fibre, present in an amount of up to 25% by
weight; and from 20 to 60% by weight of a low molecular weight
solvent that flashes off or evaporates during curing of the
composition to leave voids in the cured composition
2. A curable composition for producing a fluid permeable composite
material comprising: a particulate material; and a binding agent
including: from 25 to 50 percent by weight of an acrylic polymer
based on methacrylate; fibre, present in an amount of up to 25% by
weight; from 10 to 35% by weight of a homopolymer of an isocyanate
and corresponding isocyanate polymerizing agent for forming a
crosslinked polymer with said acrylic polymer; and from 20 to 60%
by weight of a low molecular weight solvent that flashes off or
evaporates during curing of the composition to leave voids in the
cured composition.
3. A curable composition as claimed in claim 1 wherein the low
molecular weight solvent is present in an amount of from 20 to 50%
by weight.
4. A curable composition as claimed in claim 1 wherein the low
molecular weight solvent is selected from C1 to C6 esters,
hydrocarbon solvents, or C1 to C6 ketones.
5. A curable composition as claimed in claim 4 wherein the C1 to C6
esters are selected from tert-butyl acetate or n-butyl acetate, the
hydrocarbon solvents are selected from benzene, toluene, dimethyl
benzene, ethyl benzene, cyclohexane, cumene, naphthalene,
anthracene, biphenyl, cycloterpenes and terphenyl.
6. A curable composition as claimed in claim 1 wherein the
particulate material is a stone aggregate or a ceramic
aggregate.
7. A curable composition as claimed in claim 2 wherein the acrylic
polymer based on methacrylate is selected from ethyl acrylate,
ethyl methacrylate, methacrylate copolymers, methyl methacrylic,
butyl methacrylic and methyl methacrylate copolymer.
8. A curable composition as claimed in claim 7 wherein the acrylic
polymer is methyl methacrylate copolymer and it is present in an
amount of from 25 to 40% by weight of the binding agent.
9. A curable composition as claimed in claim 8 wherein the methyl
methacrylate copolymer is present in an amount of about 30% by
weight of the binder.
10. A curable composition as claimed in claim 1 wherein the fibre
is selected from glass fibre, aramid fibre, carbon fibre or natural
fibre.
11. A curable composition as claimed in claim 10 wherein the fibre
is glass fibre having a length ranging from 0.5 mm to 6 mm fibre
length.
12. A curable composition as claimed in claim 10 wherein the glass
fibre is present in an amount of about 9% of the binder.
13. A curable composition as claimed in claim 2 wherein the
homopolymer of the isocyanate and the corresponding isocyanate
polymerizing agent is selected from hexamethylene diisocyanate
homopolymer: hexamethylene diisocyanate, methylene diphenyl
diisocyanate homoploymer: methylene diphenyl diisocyanate, toluene
diisocyanate homoploymer: toluene diisocyanate, polymeric methylene
diphenyl diisocyanate homopolymer: polymeric methylene diphenyl
diisocyanate, naphthalene diisocyanate homopolymer: naphthalene
diisocyanate, methyl isocyanate homopolymer: methyl isocyanate.
14. A curable composition as claimed in claim 2 wherein the
homopolymer of the isocyanate and the corresponding isocyanate
polymerizing agent is present in an amount of between 10 and 50% by
weight of the binder.
15. A curable composition as claimed in claim 14 wherein the
homopolymer of the isocyanate and the corresponding isocyanate
polymerizing agent is present in an amount of about 25% by weight
of the binder.
16. A process for manufacturing a fluid permeable composite
material including the steps of providing a curable composition as
claimed in claim 1, compressing the curable composition and curing
the composition at a temperature of about 10.degree. C. above the
glass transition temperature of the binder, and subsequently
reducing the temperature.
17. A process as claimed in claim 16 wherein the process includes
the step of pre-coating the particulate material with a viscosity
adjusted binding agent.
18. A process as claimed in claim 17 further including coating a
cured pre-coated particulate material with the binding agent.
19. A fluid permeable composite material made from the composition
as claimed in claim 1.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a light weight, fluid permeable
composite material suitable for use as a paver, brick, tile,
stormwater entry grate and the like, without being limited thereto.
In particular, the invention relates to a curable composition for
producing a fluid permeable composite material having high
characteristic breaking strength and flexural strength. The fluid
permeable material described in this invention, allows fluid to
flow freely through the structure without impacting on the
structural integrity of the composite material. the fluid permeable
material, and filters particulate contamination from the fluid as
it passes through the structure. This invention also relates to the
process of manufacturing the fluid permeable composite
material.
BACKGROUND OF THE INVENTION
[0002] Presently, surfaces of roads, driveways, pathways and patios
are covered with a variety of materials shaped in the form of
paving tiles or the like. Typically, such paving and paving tiles
are made of compositions such as from cementitious materials which
include blended sands, UV resistant natural oxides, optionally
natural stones and dry cement to bind the composite material
together. Alternatively the compositions could consist of clays
mixed with some or all of the above materials, and fired to high
temperatures to create the tiles or pavers. However these
traditional materials have several shortcomings.
[0003] A key disadvantage of such concrete and fired clay materials
is impermeability to fluids, in particular, water. Areas covered by
paving tiles or pavers are typically arranged such that surface
water is collected at a drainage point and directed to flow to
storm water outlets and outfall waterways, carrying with it all
manner of pollutants and contaminants collected from the impervious
surface. Upon discharge, the pollutants contaminate those outfall
waterways, rendering them unsuitable as urban water resource, and
unable to sustain normal marine life.
[0004] Further, impervious pavements with stormwater collection
systems prevent stormwater from returning to subterranean aquifers,
which are the natural collection points for stormwater, resulting
in a reduction in water levels of subterranean aquifers and
increase in salinity of the subterranean water. This renders
subterranean aquifers unsuitable as an urban water resource.
[0005] Additionally when insufficient water drainage occurs, eg.
from rain water or cleaning water, water collects or pools on the
surface. Such pooling often results in dangerous situations,
including vehicular aquaplaning on tarmacs and roads as well as
various personal injuries which occur from accidents on slippery
surfaces, eg. public building entries, car parks and the like.
[0006] Further, traditional concrete based and fired, clay pavers
exhibit brittle failure due to the nature of the elements in the
compositions, and often break suddenly under higher weight loads as
can occur with vehicular use.
[0007] The invention when used in the urban environment in place of
similar impervious composite materials, filters pollutants from
stormwater run off thus reducing pollution of outfall waterways,
and allows storm water to return to traditional subterranean
aquifers by flowing through the pavement, thereby reducing the
depletion and salination of important urban water resources.
OBJECT OF THE INVENTION
[0008] Accordingly, it is an object of the invention to provide a
hard, flexible, load bearing composite material which allows water
to freely permeate therethrough and thereby overcome or alleviate
one or more of the problems of the prior art or provide a useful
commercial alternative.
SUMMARY OF THE INVENTION
[0009] According to a first aspect of the present invention there
is provided a curable composition for producing a fluid permeable
composite material comprising:
[0010] a particulate material; and
[0011] a binding agent including: [0012] 25% and 40% by weight of
an acrylic polymer based on methacrylate; [0013] 0 to 20% by weight
of fibre, [0014] 10 to 35% by weight of a homopolymer of an
isocyanate and corresponding isocyanate polymerizing agent for
forming a crosslinked polymer with said acrylic polymer based on
methacrylate;
[0015] Preferably, the curable composition comprises 20% to 50% by
weight of a low molecular weight viscous solvent.
[0016] The particulate material may be independently selected from
various stone or ceramic aggregates. Preferably, the particulate
material is Basalt.
[0017] Suitable acrylic polymers based on methacrylates may be
selected from ethyl acrylate, ethyl methacrylate, methacrylate
co-polymers, methyl methacrylic, butyl methacrylic and methyl
methacrylate copolymer. Preferably, methyl methacrylate co-polymer
is used and is present between 20% and 50% of the binding agent.
More preferably, the methacrylate co-polymer is present between 25
and 40% and even more preferably, is 30% of the binding agent.
[0018] Fibres find use in the present composition. Suitable fibres
may be selected from fibres such as Glass fibre, Aramid fibre or
Carbon fibre, or from natural fibres which include, but are not
limited to, silk, jute, hemp, sisal. Suitably, fibres are glass
fibres. Suitable glass fibre lengths are from 0.05 mm to 6 mm fibre
length. More suitably, the glass fibre lengths are 3 mm. Suitably
the fibres are present from 0 to 25% of the binding agent. More
suitably, the inclusion of glass fibres is present at about 9% of
the binding agent. It will be appreciated by the skilled person
that if fibres other than glass are chosen, the required density of
fibre within the composition may be attained with quantities which
vary from the disclosed weight of glass fibre and the disclosed
lengths of glass fibre. For example when compared to aramid fibre,
glass fibre has a higher specific gravity than aramid fibre, so the
required density of fibre within the cured binding material will be
obtained with greater weight of glass fibre than with aramid
fibre.
[0019] The homopolymer of the isocyanate and the corresponding
isocyanate polymerizing agent may be selected from hexamethylene
diisocyanate homopolymer (homo HDI): hexamethylene diisocyanate
(HDI), Methylene diphenyl diisocyanate homopolymer: Methylene
diphenyl diisocyanate, Toluene diisocyanate homopolymer: Toluene
diisocyanate, Polymeric Methylene diphenyl diisocyanate
homopolymer: Polymeric Methylene diphenyl diisocyanate, Naphthalene
diisocyanate homopolymer: Naphthalene diisocyanate, Methyl
isocyanate homopolymer: Methyl isocyanate. Preferably, the
homopolymer of the isocyanate and corresponding isocyanate is HDI
homo:HDI and is present between 10 and 50% by weight. Preferably,
the homopolymer of the isocyanate and the corresponding isocyanate
polymerizing agent is present between 20 and 40%, and more
preferably, at about 25% of the binding agent.
[0020] Preferably, the polymerizing agent is HDI and is present at
about 0.02 to 0.005% of the binding agent.
[0021] The low molecular weight viscous solvent may be selected
from C1-C6 esters including tert-butyl acetate, n-butyl acetate,
hydrocarbon solvents which include benzene, toluene, dimethyl
benzene and its isomeric forms, ethyl benzene, cyclohexane, cumene,
naphthalene, anthracene, biphenyl, cycloterpenes, terphenyl, or
C1-C6 ketones. Preferably, the viscous solvent is butyl acetate and
is present between 0 and 60% and preferably between 20% and 50%.
More preferably, butyl acetate is present at about 37% of the
binding agent. Variables such as temperature and humidity effect
the viscosity of the mixture, and the quantity of the low molecular
weight solvent is adjusted according to prevailing environment.
[0022] Suitably the viscosity of the binding agent should be
adjusted so the binding mixture is sufficiently viscous so as to
cling to the surface of the particulate material when the
particulate matter has been coated with the binding material.
[0023] The low molecular weight solvent is also present to
facilitate the creation of maximum void area within the cured
composite material. As the composite cures, the viscous solvent
flashes off, thereby reducing the volume of the binding material
within the cured composite material and maximizing the area of void
within the composite.
[0024] According to a second aspect of the invention, there is
provided a process of manufacturing a fluid permeable composite
material including the steps of: [0025] 1. compressing the curable
composition of the first aspect; and [0026] 2. curing said
composition at a temperature of about 10.degree. C. above the glass
transition temperature of the crosslinked polymer as present in the
binding mixture. and subsequent reducing said temperature.
[0027] Preferably, the process includes the step of pre-coating the
particulate material with a viscosity adjusted binding agent.
[0028] More preferably, the process further includes the step of
coating the cured pre-coated particulate material with the binding
agent.
[0029] According to a third aspect of the present invention there
is provided an article of manufacture when produced by the process
of the second aspect.
[0030] Preferably, said article of manufacture is selected from a
paving tile, tile, brick, floor or wall covering, retaining wall
and inlet pit cover (grate). In one embodiment, the article of
manufacture is a paving tile or the like. In an alternative
embodiment, the article of manufacture is an inlet pit covering to
filter stormwater catchment prior to discharge to outfall
waterways.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] In order that the present invention may be more readily
understood and placed into practical effect, preferred embodiments
of the invention and prior art will be described, by way of example
only, with reference to the accompanying drawings, in which:
[0032] FIG. 1 is a representative drawing looking down on the fluid
permeable composite material, showing the particulate material
bound by the polymer encased fibrous binding material, and the
voids which have been created between the particulate material.
[0033] FIG. 2 is a perspective view of an inground stormwater inlet
pit covering according to a preferred embodiment of the
invention.
DETAILED DESCRIPTION
Examples
Example 1
Binding Agent Composition
[0034] Percentages are expressed in percentage by weight as are all
percentages herein unless expressly specified otherwise.
[0035] Part 1
[0036] Methacrylic copolymer, with a hydroxil functional value of
about 150 KOH/g (33.75%) is added to n-butyl acetate (33.75%). This
mixture is then added to the mixed constituents of Part 2.
[0037] Part 2
[0038] In a separate vessel, the following are combined: n-butyl
acetate (9%), 1,6Hexamethylene diioscyanate homopolymer (HDI Homo)
(approx. 13.5%), hexamethylene diioscyanate (0.005%)
[0039] Part 3
[0040] The glass fibre (10%) 3 mm fibre size is mixed into the
mixture of Part 1 and Part 2.
[0041] In this binding agent composition, substitutions of various
chemicals may be made. For example, acrylic polymers based on
methacrylates are used as cross-linking polyols. Such acrylic
polymers are suitable as they are hard and densely branched,
providing an extremely strong and durable material not obtainable
with traditional polyurethanes. In addition, unlike polycarbonates
and polyesters, these polymers have the required UV stable
properties. Suitable acrylic polymers based on methacrylates may be
selected from branched methacrylates, ethyl acrylate, methacrylate
co-polymers, methyl methacrylic, butyl methacrylic and methyl
methacrylate copolymer.
[0042] It will be further appreciated by a skilled person that
while the preferred embodiment describes a methacrylate co-polymer
with a hydroxil functional value of 150 KOH/g, the hydroxil value
may be tailored to the reacting diisocyanate such that the greater
the hydroxil value, the greater the quantity of isocyanates are
required in the reaction. Accordingly, methacrylate co-polymer
having hydroxil values ranging from 15 to 250 KOH/g may be
used.
[0043] The inventor has found that in using such copolymers
reinforced with the fibres, the resultant binding agent is
exceptionally tough, showing very high tensile strength and shore
impact resistant properties.
[0044] The mixture of Part 1 and the mixture of part 2 are combined
in a vessel, and the combined mixtures are mixed thoroughly. The
fibre is added once the mixture is thoroughly mixed
Example 2
Particulate Materials
[0045] A variety of particulate materials or aggregates may be used
in the fluid permeable composite material, inclusive of various
rock types and ceramics. Suitable rock types include Acid igneous
granitic rocks and may be selected from Granite, Adamellite,
Granodiorite, Granophyre, Rhyolite and Rhyodacite.
[0046] Also suitable are Intermediate igneous rock types and may be
selected from Diorite, Porphyry and Trachyte. Basic igneous rock
types may be selected from Basaltic rocks, inclusive of Basalt,
Dolerite and Limburgite. Further suitable are the Metamorphic rock
types and may be selected from Hornfels, Quartzite, Schist,
Phyllite, Gneiss and Greenstone. Suitably also, Sedimentary rock
types such as River Gravel may be used. Still more suitably, the
particulate material is Basalt.
[0047] While the particulate material may be regular or irregularly
shaped, the material is preferably elongate so as to provide an
increased surface area to which the binding agent may coat and an
increased surface area of contact between the particulate material.
In addition to the previously listed materials which are suitably
used as the particulate material, suitable particulate material may
also include shards or pieces of broken pottery and/or ceramics,
inclusive of, but not limited to, silica and titanium carbides,
aluminum silicates and oxides and glass. Manufactured solid
materials, such as fired clay or cured cementitious compounds may
also be used. The size of the particulate material ranges from 1 mm
to 50 mm and may be tailored to suit the purpose of which the
composite material is intended. For example, fine aggregate
particulate material of 1 mm to 5 mm is suitable for use when
formed into, for example, non-slip pool substrates and non slip
paving for areas where people walk barefoot. Medium-sized coarse
aggregate materials ranging from 10 to 20 mm are most suited for
use in stormwater filtration applications, and industrial
applications such as sound reduction paneling, tarmac, road and
bridge surfaces, footpaths and entries where non-slip surfaces are
required eg. hospitals and schools and the like. Materials coarser
than 20 mm have valuable application in self draining retaining
walls, and some stormwater and sewerage filtration
applications.
[0048] Degree of permeability of the composite material is
determined by the size and shape of the particulate material.
Rounded media of average 14 mm size has greater permeability than
an aggregate of 5 mm to 10 mm media of elongated shape. Typically,
particulate material of 10 mm to 15 mm of irregular shape has a
permeability of 30 litres per second per square metre of composite
material at a thickness of 50 mm.
[0049] It will be appreciated by a skilled person that the size,
shape and compressive strength of the particulate material will
determine the strength, porosity, filtration and sound absorption
properties of the fluid permeable composite material.
Example 3
Manufacturing Process of Fluid Permeable Composite Materials
[0050] A fluid permeable composite material is produced by the
following process using the binding agent and particulate materials
of Examples 1 and 2 respectively.
[0051] The selected particulate material is washed to remove all
foreign matter from the surface of the particulate material. This
preferable washing step involves immersing the material in water
and vibrating or agitating it to separate out unwanted foreign
matter. After removing all foreign material from the surface of the
particulate material, excess water is removed from the particulate
material surface by drainage. The particulate material is then
dried in a rotary drier until it has a moisture content of less
than 0.014%. The dried particulate material is cooled to below 30
degrees Celcius.
[0052] The cooled, dry particulate material is then pre-coated by
placing the material into a rotating drum with a measured quantity
of binding agent which has the viscosity adjusted to about 130 cps.
This is achieved by the addition of a suitable low molecular weight
solvent with good volatility such as C1-C6 esters eg. tert-butyl
acetate and n-butyl acetate to the binding material. Mixing of the
particulate material and the pre-coat binder occurs until the
particulate material's surface has been uniformly coated. This
pre-coating step establishes a uniform mechanical bond between the
particulate material and the binding material. As the particulate
material is generally porous, and as the binding material shrinks
substantially during curing, establishing a uniform mechanical bond
between the particulate material and the binding material should be
achieved as a preliminary process. Advantageously, this precoating
also seals the surface of the particulate material and ensures
moisture does not re-absorb into the particulate material. After
precoating, and until the pre-coat is dry, particulate material is
shaken periodically to prevent precoated particles from bonding to
each other. Approximate quantity of binding agent of viscosity 150
cps to particulate material for the pre-coating process is ratio of
200 ml to 11 kgs of particulate material when the particle size is
10 mm to 15 mm.
[0053] When sufficiently dry, the composite material is set aside
for a minimum of 48 hours to enable the precoat binding material to
cure.
[0054] Subsequent to this, the composite material is again mixed
with the binding agent which has not had viscosity adjusted by
addition of further low molecular weight solvents, using the
approximate binding agent to particulate material ratio of 440 ml
of binding agent to 11 kgs of particulate material when the
particulate size is 10 mm to 15 mm.
[0055] While this embodiment describes a ratio of binding agent to
particulate material of 10 to 15 mm size as ca. 440 ml: 11 kg, it
will be appreciated by a skilled person that this ratio will vary
according to the surface area of the particulate material being
used. For example, the ratio of binding agent of particulate
material (of 2 mm size) is about 480 ml: 11 kg.
[0056] The uncured composite material is transferred to a contained
space, such as a mould or area defined by forms and is vibrated
until it is uniformly distributed throughout the contained space.
This vibration process also encourages flow of binding material
around the particulate material throughout the preformed mass. The
dense fibre inclusion allows the binder to flow readily around the
particulate material but to collect at the joins between the
particulate material. Advantageously this allows build up of fibre
at the points of contact between the particulate material and
subsequently the formation of the largest possible area of join at
points of contact between particulate material.
[0057] When directed to pavers and tiles, the composite material is
then compressed in two stages. The primary stage is the application
of uniform downward pressure on the edges of the mass until the
greatest surface area of contact between material at the edge of
the contained space is achieved without crushing the particulate
material or displacing binding agent from between the particulate
material.
[0058] A secondary stage of compression is carried out by applying
uniform pressure over the total surface area of the material mass.
Compression is applied until maximum contact between the total mass
of composite material is achieved, again without crushing the
particulate material or displacing binding agent from points of
contact between materials.
[0059] It will be appreciated that the manufacturing process for
pavers and tiles requires two stages of compression as the end
product has 6 unsupported sides and is handled in sometimes abrupt
conditions before it is placed into position for use.
[0060] However, when the composite material is poured in situ for
roads, paths, retaining walls and the like, wherein at least one of
the faces is supported, eg. the bottom, and the product is not
relocated from the point of manufacture, a single stage (only) of
compression over the total area of the top surface is
undertaken.
[0061] This is typically carried out as a simultaneous
vibration/compression phase, by a flat vibrating plate dragged
across the surface whilst exerting some downward pressure.
[0062] When directed to pavers and tiles, the composite material is
`cured` by slowly raising the temperature in an oven to ca.
80.degree. C. for several minutes, preferably between 10 and 30
minutes. This temperature range is above the glass transition
temperature of 70.degree. C. of the crosslinked polymer described
in this example. A person skilled will understand that the curing
temperature is specific to the actual crosslinked polymer which has
been formed, and the effect on the glass transition temperature of
the fibrous and solvent inclusions in the polymer. The temperature
is then cooled to about 10.degree. C. lower than the glass
transition temperature, eg. 70.degree. C. before removing from the
oven. Once removed from the oven, the composite material is cooled
in dry conditions to below ca 30.degree. C. Cooling may be achieved
by blowing air across the surface of the mass with a fan. Unlike
conventional concrete and fired clay materials, the fluid permeable
composite material of the present invention does not shrink during
curing. and retains the desired dimensions and weight.
[0063] Where the composite material is poured in situ, the material
is cured by heat from a source suspended above the poured material,
raising the temperature of the material to above glass transition
temperature.
[0064] Although not wishing to be bound by any particular theory,
the present inventor reasons that the unexpectedly high strength of
the cured fluid permeable composite material, once formed, is
attributed to these processes. [0065] 1. the mechanical bond formed
between the particulate material and the binding agent during the
pre-coat process, [0066] 2. the reinforcement of the binding
material by the dense fibrous inclusion into the binding mixture.
[0067] 3. the establishment of the largest surface area of contact
between particulate matter during the compression phases. [0068] 4.
the establishment of the largest possible build up of cured binder
at the areas of joins between particulate material by the vibration
phase, and the compression phase.
[0069] It may be appreciated by a skilled person that the above
composition may be varied to accommodate various processing
conditions such as temperature and humidity which may influence
solubilities within the mixtures.
[0070] Advantageously, the fluid permeable composite material is
substantially lighter in weight than traditional composite
materials. For example, a square metre of concrete pavers of 50 mm
thick weighs ca 115 kgs. whereas a square metre of the fluid
permeable composite material of 50 mm thick weighs ca. 66 kgs. The
lighter weight is due to the area of voids within the permeable
mass. The advantages of this light weight material are ease of
transportability and workability, and less structural support
required if used above ground level such as for retaining walls,
sound proofing barriers and the like.
Example 4
Performed Test Results
[0071] Fluid Permeability
[0072] The fluid permeable composite material has unique and
advantageous physical properties as compared to traditional
concrete or other composite materials. Significantly, the present
invention provides a highly porous and fluid permeable composite
material, which allows water to flow freely through the composite
material. Typically, water flow rate is 30 litres per second
through an area of 1 square metre at 50 mm thick constructed from
an aggregate of 10 mm to 15 mm particulate material.
[0073] In an example of an application using the fluid permeable
composite material, three pavers were prepared and tested for
porosity. The pavers were sealed with aluminum flashing around the
edge of the pavers. The flashing extended 50 mm above the top
surface of the paver. Water was then flooded onto the top surface
of the paver up to maximum flow rate of 1.6 litres per second over
an exposed surface area of 370.times.370 mm. The porosity of the
paver was greater than this flow rate as evidenced by the lack of
`ponding` or pooling on the paver surface.
[0074] The fluid permeable composite material allows drainage
through the paver greater than what would be obtained with a 700
mm/hr rainfall or 700 l/m2/hr. This porosity is well in excess of
any rain fall intensity for a 5 minute duration given in standard
AS3500.3.2-1998.
[0075] Ductility, Tensile Stress and Light Weight Properties
[0076] The fluid permeable composite material exhibits ductile
failure in either compressive or tensile circumstances without the
need for reinforcing. Concrete and fired clay products without
steel reinforcing exhibit brittle failure. That is, at the point of
fracture, it breaks immediately and fails totally. Concrete with
steel reinforcing still exhibits brittle fracture, but the
reinforcing steel gives the structure ductile properties. In
contrast, the cured composite material at the point of fracture,
does not immediately break and fail, rather, it commences to fail
and will still maintain many of its properties. Failure is rupture
rather than brittle failure. Typically, a section of 350
mm.times.100 mm.times.100 mm constructed from an aggregate of 10 mm
to 15 mm particulate material and supported 25 mm from each end,
displays maximum load of 6050 N before failure.
[0077] Also advantageously, the fluid permeable composite material
achieves high tensile stress in outer fibre construction, i.e.
unlike conventional concrete or fired clay, the structure is
flexible and has substantial flexural strength. Flexural strength
is desirable as it provides the structure to carry higher loads.
Typically, a section of 350 mm.times.100 mm.times.100 mm
constructed from particulate material of 10 mm to 15 mm and
supported 25 mm from each end, displays deflection at rupture value
of 0.98 mm, elastic modulus of 1740 mpa and modulus of rupture 1.83
mpa.
[0078] The fluid permeable composite material is light weight,
weighing less than existing like composite materials. Typically
concrete pavers and the like, weighs ca. 110 kgs per square metre
at 50 mm thick, whereas the fluid permeable composite material,
when constructed from media with specific gravity of 2.8, weighs 66
kgs per square metre at 50 mm thick.
[0079] While the inventor anticipates wide application of the fluid
permeable composite material in the form of pavers and tiles, other
applications are also contemplated given the desirable properties
described above.
[0080] Storm Water Collection Pit Covers
[0081] Advantageously, the fluid permeable composite material has
high structural integrity and therefore can be used both supported
and unsupported for many engineering applications, such as
roadways, retaining walls and stormwater entry grates and pits.
[0082] In an alternate embodiment, the present invention provides a
means of filtering pollutants from storm water runoff as water
passes from paved areas into the storm water collection system.
[0083] Currently, storm water collection pits co-exist with paved
areas such as roadways and car parking stations. Water is collected
on paved surfaces during rainfall and flows to the lowest point on
that paved area. It is intended that runoff water from paved areas
be collected before pooling to avoid flooding. Runoff water is
collected at various points on the paved area and directed through
a system of under ground pipes to outfall areas where water is
discharged into waterways. Runoff water transfers from paved areas
to the underground pipe system through storm water collection pits.
Typically these are of a box construction, usually concrete, and
installed across the flow of runoff water, below the surface level
of the paved area. Runoff water flowing toward low points in paved
areas, drops into the collection boxes.
[0084] Collection boxes have two types of entry, inground and side
entry. Inground entry is at the same level as the pavement and are
protected by metal grates strong enough to support vehicle weight
and with openings large enough for required water capture. However,
these metal grates have been shown to be unsafe for pedestrian and
cycling traffic. In addition, they have no means of pollution
filtration, i.e. existing metal inlet grates do not filter
pollutants from stormwater as it enters the collection pits.
[0085] Side entry openings are vertical openings, usually built
into the side of gutter drains, and are uncovered. Protective
grates or pollution filtration covers are not available for side
entry openings. As storm water runoff travels across paved
surfaces, gross pollutants, eg. cigarette butts, plastic bags,
paper and leaf litter are collected and deposited into collection
pits.
[0086] The inventor anticipates that the fluid permeable composite
material may be used to filter pollutants from stormwater prior to
entry into the collection system by providing a stormwater cover at
collection box entry points. An embodiment of a typical storm water
cover is shown in FIG. 1. The cover 10 includes the fluid permeable
composite material 12 housed by a steel frame 14. Dimensions may be
varied according to the type, size and shape of stormwater
collection pit entry opening eg. whether the opening is in-ground
or Lintel (side entry) type, type of traffic which normally
transverse the collection pit, if any, and water capture
requirement of the collection pit.
[0087] Advantageously, use of the fluid permeable composite
material in this way allows rain and storm water to collect and
drain through the surface. Gross pollutants, such as plastic bags
and bottles, leaf litter, cigarette butts and the like are left on
the surface, and some micro contaminants such as hydrocarbons,
heavy metals and carbon monoxide solids are trapped within the
permeable mass of the composite material. Water entering outfall
systems is therefore pre-filtered before entering outfalls, with
obvious benefits to the environment
[0088] Sound Reduction Applications
[0089] The inventor further anticipates that the fluid permeable
composite material may find application as an effective sound
reduction material. When sound energy is directed at the fluid
permeable composite material, some will deflect from the facets of
the irregular composite surface and some will enter the voids and
be absorbed within the composite material. Typically, a composite
material of 50 mm thick of 10 mm to 15 mm irregular shaped
particulate material provides considerable sound reduction, eg.
from 25 db to 40 db.
[0090] Effectiveness as a sound reduction composite material is
determined by the size and shape of the media, and by the
percentage of void within the permeable mass. Irregular media shape
and greater percentage of void within the mass, increases the
effectiveness in reduction of sound. It is anticipated that the
composite material would find application in large commercial
premises, such as indoor pool complexes, auditoriums, roadside
sound reduction panels and in dividing walls between higher density
commercial and residential properties. It will be appreciated by
the skilled person that the present invention is not limited to the
embodiments described in detail herein, and that a variety of other
embodiments may be contemplated which are nevertheless consistent
with the broad spirit and scope of the invention.
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